Diffusion lab

Today in my science class i did a lab on Diffusion and Osmosis. This experiment used cornstarch and iodine. We put cornstarch in a plastic bag and tied it, then put it in a mixture of iodine and water. We wanted to see if the bag was permeable, which means it lets some materials through. It let in only a little bit of iodine, however, and it turned the cornstarch light yellow, and light purple on the bottom where it was touching the bottom of the beaker. Ending result- not very effective.